A surgical operation in which the glenoid articular surface of a scapula is replaced by a concave glenoid prosthetic component is a difficult procedure, particularly because of the ligaments around the shoulder. It has been found that, depending on the geometry of the articulation and/or the position of implantation of such a glenoid component, the glenoid component may be at risk of coming loose on account of the change in forces that are applied to the glenoid component during subsequent movements of the shoulder that has been fitted with the prosthesis.
Currently, orthopedic surgeons select a glenoid component from a plurality of implants having geometries, especially sizes, that differ slightly from one another. They choose the glenoid component by empirically estimating the position of implantation of the selected glenoid component by visually assessing the geometry of the glenoid surface of the patient being operated on. The surgeon seeks to select the prosthetic component and implant it on the scapula in such a way that this component reproduces the original articular glenoid surface of the patient. However, this method can be imprecise, in particular, when the original glenoid cavity of the patient is too badly damaged to provide an indicator that can be directly exploited by surgical observation.